1. Technical Field
This application relates to an apparatus and method for guidewire retrieval for over the wire insertion of catheters.
2. Background of Related Art
Hemodialysis is a well known method of providing renal (kidney) function by circulating blood. A dialysis catheter is typically inserted through the jugular vein and maneuvered into position through the superior vena cava into the right atrium. Blood is withdrawn from the patient's body through the dialysis catheter and transported to a dialysis (kidney) machine. In the dialysis machine, the waste products are removed, and the filtered blood is returned to the patient's body through the catheter.
Prior art catheters such as the MedComp Ash Split catheter are inserted through introducer sheaths which are then manually separated (peeled) and removed from the site. These dialysis catheters require numerous steps for insertion because of the tear away sheath. The multiple insertion steps can be summarized as follows:                1. an introducer needle is inserted through a first incision site (first opening) to properly locate (access) the vessel, e.g. the right internal jugular vein;        2. a guidewire is inserted through the needle into the internal jugular vein and down through the superior vena cava into the inferior vena cava;        3. the introducer needle is withdrawn leaving the guidewire in place;        4. a tear away (peel away) sheath and dilator are inserted over the guidewire and through the first incision site to provide an access port for the dialysis catheter into the jugular vein, superior vena cava and right atrium;        5. a second incision is made in the chest wall to create a second opening;        6. a trocar is attached to the distal end of the dialysis catheter;        7. the trocar and dialysis catheter are pushed through the second incision and advanced to bluntly dissect the subcutaneous tissue to exit the first incision (opening) which was created by the introducer needle, thereby creating a subcutaneous tissue tunnel between the first and second openings;        8. the trocar is detached from the dialysis catheter leaving the catheter in place extending from the second opening, through the tissue tunnel and out the first opening;        9. the dilator and guidewire are removed, leaving the tear away sheath in place in the first incision which has been expanded by the dilator;        10. the dialysis catheter, which is protruding from the first incision, is inserted through the tear away sheath and advanced so its distal portion is positioned in the right atrium;        11. the sheath is separated, i.e. split, by pulling the tabs apart, and then pulled upwardly away from the dialysis catheter and removed from the body, leaving the catheter in place; and        12. the second incision is closed and the dialysis catheter, which is connected through tubes to the dialysis machine, is left in place an extended period of time to provide blood circulation to and from the dialysis machine.        
Alternatively, in the foregoing method, the trocar can be forced through a third incision exiting adjacent the first incision, and then the catheter inserted through the second and third incisions and the introducer sheath positioned in the first incision.
This multiple step process of inserting the prior art dialysis catheter is time consuming and complicates the surgical procedure. These multiple steps also add to the cost of the procedure, not only because of the additional surgeon's time but because additional components, such as the tear-away sheath, are required which increases the overall cost of the catheter system. Also, removal of the dilator increases the tendency of the sheath to kink causing difficulties in catheter insertion.
The use of the tear away sheath is also problematic. The tear-away style sheath has lines of weakness to separate the sheath as it is pulled apart by the pull tabs for removal. However, the sheath can potentially cause damage to the vessel wall as it is being pulled apart and can cause infection. Moreover, pulling the sheath laterally can enlarge the incision, thereby increasing the difficulty of closing the incision at the end of the procedure. Also, since the sheath is pulled in the proximal direction for removal, it could pull the catheter proximally as well, thereby pulling it away from the desired site, and requiring repositioning. The edges of the tear away can also lacerate the surgeon's glove and finger. Over dilation caused by the sheath can also cause blood leakage.
An additional potential risk with utilizing tear away sheaths is that air embolism can occur. During the time the surgeon withdraws the dilator from the sheath and inserts the catheter, a passageway through the sheath to the vessel is open. If the patient inhales during this catheter exchange, an air bubble can enter the vascular system and obstruct the vessel, potentially causing stroke or even death.
It would therefore be advantageous if a dialysis catheter insertion method could be provided which reduces some of the foregoing procedural steps, thereby decreasing the complexity of the procedure and decreasing the hospital and surgeon costs. It would also be advantageous if such dialysis catheter insertion method could be provided which would be less traumatic and avoid the foregoing problems associated with the use of a tear-away sheath.
To achieve such insertion, it would be necessary to ensure the catheter has sufficient stiffness to be pushed through the subcutaneous tissue tunnel and vessels into the right atrium. However, such stiffness must not significantly reduce catheter flexibility which would render navigation of the catheter difficult and potentially traumatic to the vessels.
The need therefore exists for a dialysis catheter having the necessary stiffness, while retaining sufficient flexibility, to enable the advantageous insertion characteristics described herein, e.g. reduction of catheter insertion time, simplification of the catheter insertion process, and elimination of a peel-away introducer sheath.
The catheter and insertion methods disclosed in co-pending commonly assigned Ser. No. 10/279,468, filed Oct. 24, 2002, the contents of which is incorporated herein by reference in its entirety, satisfies the above-mentioned needs and provides the foregoing advantages by providing a complete over-the-wire catheter insertion method which eliminates the need for a peel-away sheath. As disclosed in this application, a trocar is provided for retrieving the guidewire and passing it through the tissue tunnel for subsequent guidance of the catheter. The present invention discloses various trocars for achieving placement of the guidewire through the subcutaneous tissue tunnel. Such placement of the guidewire also advantageously enables over the wire insertion of different types of catheters.